(a) Technical Field
The present invention relates to a sound absorbing and insulating material with superior moldability and appearance and a method for manufacturing the same. The sound absorbing and insulating material may comprise: (1) an inner layer 1 comprising a first nonwoven fabric comprising a heat-resistant fiber and a binder uniformly distributed inside the first nonwoven fabric and maintaining the three-dimensional structure inside the first nonwoven fabric, and (2) an outer layer (2′, 2″) formed of a second nonwoven fabric comprising a heat-resistant fiber. Particularly, the outer layer may be stacked on one or both sides of the inner layer. Accordingly, the sound absorbing and insulating material of the present invention may have superior sound-absorbing property, flame retardancy, heat resistance, heat-insulating property and high-temperature moldability. In addition, deterioration of surface appearance caused by leakage of the binder may be prevented due to the presence of the outer layer.
(b) Background Art
Noise, as an unwanted side effect of industrial development, causes gradually more damages. Accordingly, various methods have been provided taken to prevent noise. As a way of such noise prevention, researches for developing new sound absorbing and insulating materials capable of arresting, absorbing or insulating sound have been conducted in various ways.
Representative industrial sectors requiring sound absorbing and insulating materials include electric appliances such as an air conditioner, a refrigerator, a washing machine, a lawn mower and the like, transportation such as a vehicle, a ship, an airplane and the like, construction materials such as a wall material, a flooring material and the like, and so forth. The sound absorbing and insulating material may also be required in other various industrial fields, too. In general, the sound absorbing and insulating materials used in industries require, in addition to good sound-absorbing property, reduced weight, flame retardancy, heat resistance and heat-insulating property, depending on particular applications. Particularly, flame retardancy and heat resistance may be additionally required, particularly when those materials are used for sound absorbing and insulating materials used in engines, exhaust systems and the like where a high temperature of about 200° C. or greater is maintained. For example, an aramid fiber has been used gaining attentions for sound absorbing and insulating materials having superior heat resistance.
In addition, in order to provide functionalities such as flame retardancy, water repellency and the like to a sound absorbing and insulating material, many sound absorbing materials made of a nonwoven fabric containing aramid fibers and a functional skin material may be stacked.
For example, Korean Patent Publication No. 2007-0033310 discloses a flame-retardant sound absorbing material wherein a nonwoven fabric layer in which a heat-resistant short aramid fiber and a short thermoplastic polyester fiber are bridged and a skin material layer formed of a wetlaid nonwoven fabric consisting of a short aramid fiber are stacked.
In addition, Japanese Patent Publication No. 2007-0039826 discloses a water-repellent sound absorbing material wherein a nonwoven fabric layer of a heat-resistant short aramid fiber or a blend of a short aramid fiber and a short thermoplastic polyester fiber and a skin material layer treated with a water repellent are stacked.
Further, Japanese Patent Publication No. 2007-0138953 discloses a heat-resistant sound absorbing material wherein a nonwoven fabric layer consisting of a heat-resistant aramid fiber and a skin material layer formed of a fiber sheet containing a heat-resistant aramid fiber are stacked.
Since those sound absorbing materials described above have a structure comprising a skin material layer laminated on one side of a nonwoven fabric to provide functionalities such as flame retardancy, water repellency and the like, a hot pressing process for integrating the nonwoven fabric layer and the skin material layer may be necessary. Consequently, the overall process may be complicated and troublesome and a flame retardant, a water repellent and the like included as additives may cause production of toxic gases as a result of combustion during the hot pressing process. In addition, deformation of the internal structure of the nonwoven fabric that may occur during the hot pressing process can lead to deterioration of sound-absorbing property.
The description provided above as a related art of the present invention is just merely for helping understanding of the background of the present invention and should not be construed as being included in the related art known by those skilled in the art.